Middle French or Medieval Latin; Middle French valide, from Medieval Latin validus, from Latin, strong, potent, from valēre
- Date: 1571
- 1 : having legal efficacy or force; especially : executed with the proper legal authority and formalities <a valid contract>
- 2 a : well-grounded or justifiable : being at once relevant and meaningful <a valid theory>
sound, cogent, convincing, telling mean having such force as to compel serious attention and usually acceptance. valid implies being supported by objective truth or generally accepted authority <a valid reason for being absent>
The term validity in logic (also logical validity) is largely synonymous with logical truth, however the term is used in different contexts. Validity is a property of formulas, statements and arguments. A logically valid argument is one where the conclusion follows from the premises. An invalid argument is where the conclusion does not follow from the premises. A deductive argument may be valid but not sound. In other words, validity is a necessary condition for truth of a deductive syllogism but is not a sufficient condition.